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We congratulate Drs. Srivatsan and colleagues on their paper examining the effects of endovascular coiling of unruptured intracranial aneurysms (UIAs) on cognition using the Montreal Cognitive Assessment (MoCA).1 In particular, we appreciate the efforts made to sample the patients at multiple time points including pre-intervention and at 1-month and 6-months post-intervention. The study found that coiling did not diminish neurocognitive function per the MoCA, with there also being no correlation between follow-up MoCA scores and imaging findings, the overall results being comparable to the authors’ previous paper on MoCA scores following flow diversion for UIAs.2 Intriguingly, the MoCA scores at baseline were on average below the typical cut-off of 26 points, especially given the relatively young population (mean age 55.5 years).
However, as acknowledged by the authors, the ability of the study to discern post-coiling imaging changes was limited by both the small subset of the population that received follow-up imaging (17 of 33 patients, 51.5%) and the smaller subset that underwent MRI (9 patients, 27.3%).1 Diffusion-weighted imaging (DWI) sequences of MRI are most sensitive to identifying post-procedural ischemic injury following neuro-interventional procedures like coiling.3 DWI lesions occur quite frequently; for example, in the ENACT trial (Evaluating Neuroprotection in Aneurysm Coiling Therapy), 68% of patients had new lesions post-procedure, with an average o...
However, as acknowledged by the authors, the ability of the study to discern post-coiling imaging changes was limited by both the small subset of the population that received follow-up imaging (17 of 33 patients, 51.5%) and the smaller subset that underwent MRI (9 patients, 27.3%).1 Diffusion-weighted imaging (DWI) sequences of MRI are most sensitive to identifying post-procedural ischemic injury following neuro-interventional procedures like coiling.3 DWI lesions occur quite frequently; for example, in the ENACT trial (Evaluating Neuroprotection in Aneurysm Coiling Therapy), 68% of patients had new lesions post-procedure, with an average of 4.3 new lesions in the NA-1 arm and 6.7 lesions in the placebo arm when considering just the 147 patients with UIAs.4 Future studies will need to examine the relationship between the burden of such DWI lesions and post-procedural cognitive outcomes in further detail.
Furthermore, although the MoCA is a useful global assessment of cognitive impairment, we suspect that it may have more limited sensitivity in identifying mild post-procedural cognitive changes. As the studies by Drs. Strivatsan and colleagues with post-coiling and post-flow-diversion outcomes have shown, any potential changes are likely to be subtle. As we seek to uncover the phenotype of potential cognitive deficits after endovascular procedures for UIAs, we may seek guidance from the existing literature on vascular cognitive impairment (VCI), which is known to have a preponderance of executive dysfunction, including slowed information processing, impaired set-/task-shifting, and deficits in working memory.5 6 To help assess such domains with greater granularity, the National Institute of Neurological Disorders and Stroke (NINDS) and the Canadian Stroke Network (CSN) have proposed cognitive testing protocols as part of the NINDS-CSN VCI Harmonization Standards.7 Of the 5-minute, 30-minute, and 60-minute protocols proposed, the 30-minute test protocol (applied in the ENACT trial)4 appears to offer a helpful balance of length and granularity, with specific measures of the aforementioned domains like the Controlled Oral Word Association Test (COWAT – phonemic fluency), semantic fluency, Digit Symbol-Coding, the Hopkins Verbal Learning Test (HVLT), the Trail Making Test, as well as brief assessments of neuropsychiatric symptoms through the Center for Epidemiologic Studies – Depression (CES-D) scale and the Neuropsychiatric Inventory, Questionnaire Version (NPI-Q).7 Future studies of post-procedural cognitive changes should seek to incorporate some or all of these additional tests into their follow-up testing protocols.
1. Srivatsan A, Mohanty A, Saleem Y, et al. Cognitive outcomes after unruptured intracranial aneurysm treatment with endovascular coiling. J Neurointerv Surg 2020 doi: 10.1136/neurintsurg-2020-016362 [published Online First: 2020/07/24]
2. Wagner K, Srivatsan A, Mohanty A, et al. Cognitive outcomes after unruptured intracranial aneurysm treatment with flow diversion. J Neurosurg 2019:1-6. doi: 10.3171/2019.9.JNS191910 [published Online First: 2019/11/30]
3. Iosif C, Camilleri Y, Saleme S, et al. Diffusion-weighted imaging-detected ischemic lesions associated with flow-diverting stents in intracranial aneurysms: safety, potential mechanisms, clinical outcome, and concerns. J Neurosurg 2015;122(3):627-36. doi: 10.3171/2014.10.JNS132566 [published Online First: 2015/01/07]
4. Hill MD, Martin RH, Mikulis D, et al. Safety and efficacy of NA-1 in patients with iatrogenic stroke after endovascular aneurysm repair (ENACT): a phase 2, randomised, double-blind, placebo-controlled trial. Lancet Neurol 2012;11(11):942-50. doi: 10.1016/S1474-4422(12)70225-9
5. Garrett KD, Browndyke JN, Whelihan W, et al. The neuropsychological profile of vascular cognitive impairment--no dementia: comparisons to patients at risk for cerebrovascular disease and vascular dementia. Arch Clin Neuropsychol 2004;19(6):745-57. doi: 10.1016/j.acn.2003.09.008 [published Online First: 2004/08/04]
6. Nyenhuis DL, Gorelick PB, Geenen EJ, et al. The pattern of neuropsychological deficits in Vascular Cognitive Impairment-No Dementia (Vascular CIND). Clin Neuropsychol 2004;18(1):41-9. doi: 10.1080/13854040490507145 [published Online First: 2004/12/15]
7. Hachinski V, Iadecola C, Petersen RC, et al. National Institute of Neurological Disorders and Stroke-Canadian Stroke Network vascular cognitive impairment harmonization standards. Stroke 2006;37(9):2220-41. doi: 10.1161/01.STR.0000237236.88823.47